P0273
UniversalCylinder 5 Injector Circuit Low
Medium SeverityThis code indicates that the Engine Control Module (ECM) has detected a lower-than-expected voltage or an open circuit in the electrical circuit leading to the fuel injector for cylinder 5. This typically results in the fuel injector not firing correctly, leading to engine performance issues.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical work on your vehicle. Fuel systems are under pressure; follow proper procedures for depressurization to avoid fuel spray and potential fire hazards. Wear appropriate eye protection.
Common Symptoms
- Check Engine Light illuminated
- Engine misfire
- Rough idle
- Poor acceleration
- Reduced fuel economy
- Engine hesitation
Common Causes
- Faulty fuel injector for cylinder 5
- Open circuit or short to ground in the wiring harness to cylinder 5 injector
- Corroded or loose electrical connector at the injector or ECM
- Faulty Engine Control Module (ECM)
Frequently reported on: General/Universal
Diagnostic Steps
- Inspect the wiring harness leading to the cylinder 5 fuel injector for any visible damage, chafing, or corrosion.
- Check the electrical connector at the cylinder 5 fuel injector and the ECM for looseness, bent pins, or corrosion.
- Using a multimeter, test the resistance of the cylinder 5 fuel injector; compare it to manufacturer specifications and other injectors.
- Using a multimeter, check for proper voltage supply to the cylinder 5 fuel injector connector with the key on.
- If injector resistance and voltage supply are within spec, consider replacing the cylinder 5 fuel injector.
- Clear the DTCs and test drive the vehicle to see if the code returns.
👨🔧 When to Call a Professional
If basic diagnostic steps like checking wiring and connectors do not resolve the issue, or if you suspect an internal fault with the ECM, it is best to consult a professional mechanic. Complex electrical diagnosis requires specialized tools and expertise.
Commonly Asked Questions
What does 'circuit low' mean for a fuel injector?
'Circuit low' means the Engine Control Module (ECM) is detecting a lower-than-normal voltage or an open circuit in the electrical path to the fuel injector. This can prevent the injector from operating correctly.
Can I drive with a P0273 code?
It is not recommended to drive for extended periods with a P0273 code. A misfiring cylinder can cause further damage to the engine, catalytic converter, and significantly impair vehicle performance and safety.
Is it possible this is an ECM issue?
While less common than a faulty injector or wiring, a problem with the Engine Control Module (ECM) can cause a P0273 code if the ECM is not sending the correct signal or voltage to the injector. This should be a last resort diagnosis after ruling out the injector and wiring.
How can I test the fuel injector itself?
You can test the fuel injector by checking its electrical resistance with a multimeter. Compare the reading to your vehicle's specifications and the readings from other injectors. A reading outside the specified range or significantly different from others indicates a faulty injector.
What tools do I need to diagnose P0273?
To diagnose P0273, you will typically need a multimeter for electrical checks (resistance, voltage), a basic set of wrenches and sockets, and potentially an OBD-II scanner to clear codes and monitor live data.